Am Dienstag, 24. April 2007 13:19 schrieb Wael Adel:
> so these are the required modifications required to wait until the urb
> is finished then i can transfer the read data to the user-space
>
> ***********************************************************************************************************************
> static void skel_read_bulk_callback(struct urb *urb, struct pt_regs *regs)
> {
> struct usb_skel *dev;
> complete((struct completion *)urb->context);
> dev = (struct usb_skel *)urb->context;
>
>
> /* sync/async unlink faults aren't errors */
> if (urb->status &&
> !(urb->status == -ENOENT ||
> urb->status == -ECONNRESET ||
> urb->status == -ESHUTDOWN)) {
> dbg("%s - nonzero write bulk status received: %d",
> __FUNCTION__, urb->status);
> }
>
> /* free up our allocated buffer */
> usb_buffer_free(urb->dev, urb->transfer_buffer_length,
> urb->transfer_buffer, urb->transfer_dma);
Don't free the buffer here. You want to read from it.
> up(&dev->limit_sem);
> }
>
> static ssize_t skel_read(struct file *file, const char *user_buffer,
> size_t count, loff_t *ppos)
> {
> struct completion done;
You need to call init_completion() on that before you use it.
> struct usb_skel *dev;
> int retval = 0,readbytes;
> struct urb *urb = NULL;
> char *buf = NULL;
> size_t readsize = min(count, (size_t)MAX_TRANSFER);
>
> dev = (struct usb_skel *)file->private_data;
>
> /* verify that we actually have some data to write */
read that would be
> if (count == 0)
> goto exit;
>
> /* limit the number of URBs in flight to stop a user from using up all
> RAM */
> if (down_interruptible(&dev->limit_sem)) {
> retval = -ERESTARTSYS;
> goto exit;
> }
>
> /* create a urb, and a buffer for it, and copy the data to the urb */
> urb = usb_alloc_urb(0, GFP_KERNEL);
> if (!urb) {
> retval = -ENOMEM;
> goto error;
> }
>
> buf = usb_buffer_alloc(dev->udev, readsize, GFP_KERNEL,
> &urb->transfer_dma);
> if (!buf) {
> retval = -ENOMEM;
> goto error;
> }
>
> /* initialize the urb properly */
> usb_fill_bulk_urb(urb, dev->udev,
> usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
> buf, readsize, skel_read_bulk_callback, dev);
You must pass a pointer to done, not dev.
> urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
>
> /* send the data out the bulk port */
> retval = usb_submit_urb(urb, GFP_KERNEL);
> if (retval) {
> err("%s - failed submitting write urb, error %d", __FUNCTION__,
> retval);
write?
> goto error;
> }
>
> wait_for_completion(&done);
>
> if ( copy_to_user(user_buffer, dev->bulk_in_buffer, readbytes) )
> retval = -EFAULT;
> else
> retval = readbytes;
1. Here you need to free the URB and the buffer
2. You must deal with your device delivering less bytes than you asked for
You can use urb->actual_length
> return retval;
>
> /* release our reference to this urb, the USB core will eventually
> free it entirely */
> usb_free_urb(urb);
>
> exit:
> return readsize;
>
> error:
> usb_buffer_free(dev->udev, readsize, buf, urb->transfer_dma);
> usb_free_urb(urb);
> up(&dev->limit_sem);
> return retval;
> }
> *********************************************************************************************************************
> is it right? or there is something else i should adjust.
> thanks in advance.
>
> >
> > HTH
> > Oliver
> > --
> > SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
> > This signature is a legal requirement
> >
>
--
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
This signature is a legal requirement
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